Bone bed drilling template

ABSTRACT

A method and device for ensuring better placement of an implant, such as an implant that is affixed via bone bed drilling to a recipient&#39;s skull. In particular, the technology comprises an apparatus and method of deploying the same that can lead to an improved goodness of fit of the implant. The apparatus and process of the present disclosure are particularly applicable to affixing auditory prostheses such as cochlear implants. The implant is provided with a template that has the same dimensions as the implant that is to be affixed. This template has a dye-impregnated material on its distal surface that is used during bone bed drilling to identify bony spots that have to be drilled away to get a flat surface and a better alignment of the implant with the bone bed. The template may also be provided in kit form.

TECHNICAL FIELD

The technology described herein generally relates to placement ofmedical implants, and more particularly relates to optimizing thecloseness of fit of an implant to an area of bone.

BACKGROUND

Bone bed drilling is a time consuming task during implant surgery, inpart because of the precision required to ensure a good fit between theimplant and the bone surface. The surface of the bone bed to which animplant is attached needs to be smooth and flat, in order to minimizecomplications such as biofilm formation in interstices between thesurface of the bone and the surface of the implant if the bone surfaceis uneven, or inadvertent relocation of the implant after surgery due topoor contact adhesion if the bone surface is not flat enough.

For an implant that is affixed to a patient's skull these problems areparticularly acute since the surface of the skull is curved, yet thesurface of an implant is flat. So if an implant is placed directly on tothe surface of the skull, it can rock because it is flat relative to thecurved section of skull. The surgeon therefore needs to plane away aflat surface of the bone to accommodate the implant in a rigid manner.Additionally, the surface of the recessed portion needs to be as smoothas possible so that the area of contact with the implant is maximizedover the recessed region and the implant does not wobble due tounevenness of the surface, and there are no cavities between the bonesurface and the adjacent implant surface.

In many types of implant such as auditory prostheses, the portion of theimplant that is in direct contact with the bone is a receiver/stimulatorunit: if this item does not have good contact with the bone at allpoints on its surface, it can shift its position after surgery, leadingto a degradation or variability in its performance, and a continual needto recalibrate it. Furthermore, cavities, if present underneath thereceiver/stimulator, can lead to biofilm formation and higher infectionrisks for the subject, in the post-surgical phase. Biofilm formation isencouraged when there is a pocket of air between the implant and thebone, in which bacteria can grow. Such bacteria can spread and make anincreased area of infection, thereby having a harmful impact on theimplant recipient. There can be a similar propensity for biofilmformation in any imperfections that may exist on the edges of the bonebed: it is important that the side walls of the drilled out area areperpendicular to the flat area which was drilled out and this may not beeasy to gauge.

Other methods for reducing biofilm include coating the surface of theimplant with an anti-bacterial substance, or a material such as asilicone that fills the voids when the implant is affixed, as well as bydesigning the implant so that it has smooth surfaces. These approaches,however, do not address the goodness of fit of the implant.

Some implants have used a hydroxyapatite cement to affix it but thesubstance expands on setting and so is less desirable when the implantmust fit snugly in the bone bed. Other ways of fixing an implant are byusing a titanium bridge, or a suture above the implant, but thesemethods do not necessarily work well for all types of implant and maynot address the issue of biofilm formation.

Many implant kits are provided with a surgical kit containing variousimplant templates that can be used by surgeons to check the depth,shape, and flatness of the bone bed during drilling and prior toattachment of the implant. Some examples are produced by Cochlear,Limited (e.g., the CI24RE implant template). In many instances, morethan one template is required for the same implant because, the sametemplate cannot necessarily be used to define the perimeter of the areabefore any drilling is done as the template that is used to gauge theproper depth of the recessed area.

FIGS. 1A, 1B, 1C, and 1D show the actuator 101 of an exemplary acousticimplant, its fixation system 111, its position in situ on a patient'sskull 103, and a template 121 to assist the surgeon in drilling arecessed area of bone in which to position fixation system 111, and thecorresponding receiver/stimulator 141. In this example, fixation system111 is used to hold actuator 101 in the mastoid (bone behind therecipient's ear), as shown in FIG. 1B, and as further described herein.The receiver/stimulator unit that communicates with actuator 101 is notshown in FIGS. 1A-1C.

However, while implant templates do help a surgeon to create a flatsurface by trial and error, they do not make it clear to the surgeonwhere to flatten the bone, or improve the perpendicularity of the sidesof the bone bed, during surgery. Therefore, during bone bed drilling,surgeons often struggle to create a flat surface, and may end upunnecessarily drilling away additional bone at the wrong spots.

In the absence of any other way in the art to address the foregoingproblems, there is accordingly a need for a method and device forfacilitating reliable placement of a bone implant, in order to improvethe efficiency of the surgical process, as well as ensure a greaterfidelity of the implant's attachment to the bone surface.

The discussion of the background herein is included to explain thecontext of the technology. This is not to be taken as an admission thatany of the material referred to was published, known, or part of thecommon general knowledge as at the priority date of any of the claimsfound appended hereto.

Throughout the description and claims of the application the word“comprise” and variations thereof, such as “comprising” and “comprises”,is not intended to exclude other additives, components, integers orsteps.

SUMMARY

The instant disclosure is directed to the better placement of a part ofan implant, such as an implant that is affixed via bone bed drilling ofa recipient's skull in a manner that permits part of the implant, saythe actuator, to be properly positioned. In particular, the disclosurecomprises an apparatus and method of deploying the same that can lead toan improved goodness of fit of at least part of the implant to therecipient's skull. The apparatus and process of the present disclosureare particularly applicable to affixing auditory prostheses such ascochlear implants.

The apparatus comprises one or more surgical templates that has the samedimensions as the part of the implant that is to be affixed to therecipient. The templates are used during bone bed drilling to identifybony spots that have to be drilled away to get a flat surface and sidesthat are perpendicular to the bottom, and hence a better alignment ofthe implant receiver/stimulator with the skull.

The present disclosure provides for surgical templates that can be usedto improve the goodness of fit, and minimize biofilm formation, whenaffixing an implant on a recipient's skull. The templates can be usedwith many types of implantable audio prosthetic devices, such ascochlear implants, middle ear implants, bone conduction auditoryimplants, subcutaneous implants, ossio-integrated steady state implants,and direct acoustic cochlear implants.

The templates of the present disclosure are loaded with adye-impregnated material on a distal surface. When this material makescontact with the recipient's bone, the dye is transferred to the bone atthe points where contact is made. Thus a template can be used, in thefirst instance (before drilling commences) to delineate the area to bedrilled. While the recessed area is being drilled out, a template can beinserted one or more times into the drilled area to provide anindication to the surgeon of any unevenness in the surface and/or sidesof the drilled region. Such templates are particularly suited for bonebed drilling on a recipient's skull but can in principle be used for animplant affixed to any bone in the human body.

The present disclosure further includes a process for using a surgicaltemplate, having a dye-impregnated material on its distal surface, todelineate an area of a recipient's skull to be drilled, and portions ofthe bone bed to be drilled during surgery.

The present disclosure additionally includes a surgical kit thatincludes an implant and one or more implant templates having adye-impregnated material on a distal surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D show the fixation system of an implant (1A), its location insitu (including the actuator) (1B), a fixation system template (1C), andthe entire implant including the actuator and a correspondingreceiver/stimulator (1D), as found in the prior art.

FIG. 2 shows a schematic of a dye template in use on a recipient'sskull, checking the goodness of fit.

FIGS. 3A and 3B show schematics of various implantation environments.

FIG. 4 shows a template having a dye material attached to a mountinglayer that clips to the template via a press-button arrangement.

FIG. 5 shows a kit having a number of templates.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The instant technology is directed to methods and devices to improvegoodness of fit of a medical implant that is designed to be affixed to arecipient's bone. The technology further includes methods and devicesfor reducing the possibility of biofilm formation in small unwantedrecesses that can arise between the surface of the implant and thesurface of the bone when drilling the portion of bone needed toaccommodate the implant.

Use of a template when affixing a bone implant

It is instructive to first describe a method and device of affixing animplant, as used in the art, in conjunction with FIGS. 1A, 1B, 1C, and1D, which illustrate the nature of the technical problem for anexemplary auditory prosthesis, Codacs™ direct acoustic cochlearstimulator from Cochlear Limited, Sydney, Australia. It would beunderstood to those of skill in the art that the general principles ofaffixing such an implant apply to other types of implant, and are notlimited to auditory prostheses.

In FIG. 1B, the actuator 101, shown in situ adjacent to a recipient'sauditory canal 104, and which stimulates fluid in the recipient'scochlea 105, is held in place by a fixation system 111. Thecorresponding receiver/stimulator 141 is shown in FIG. 1D, forillustration. Artificial incus 143 is connected to a conventional stapesprosthesis 106, which is inserted into the recipient's cochlea. Leadassembly 145 provides electrical connectivity between the actuator andthe receiver/stimulator assembly 141. In this embodiment, thereceiver/stimulator comprises various electronic circuitry 147, a magnet148, and receiver coil 149.

Fixation system 111 is shown in elevation view in FIG. 1A, and in planview from the side, in FIG. 1B. Fixation system 111 comprises threeportions: an attachment portion (bone plate) 107 that lies flat on therecipient's skull and contains a number of holes 116 (seven holes in theembodiment shown), through which screws 109 are inserted, in order toattach the system to the recipient's skull. A pedestal 113, such ascomprising a ball joint 118 and ball clamp screw 120, is situated into adrilled out recessed area of the recipient's skull. Clamping mechanism117 is not affixed to the recipient's skull but holds actuator 101 inits position in the mastoid cavity, wherein it can function effectively.A clamp screw 115 can be used to adjust the position of clamp 117 aswell as to secure it in its optimal position. Elastic blade 119 is forlocking clamp screw 115.

When affixing fixation system 111 to a recipient's skull, it isnecessary to drill out a recessed area of skull that can accommodateball joint portion 113. The size of the area to be drilled is determinedby the model of implant (implants are not designed or tailored for theindividual recipient).

While the outer perimeter of the regions to be drilled can usually bedefined quite accurately, the depth of the recessed area is moredifficult to drill reliably. Accordingly, the surgeon typically uses agauge, or template, 121 to test the goodness of fit of the portionsdrilled. Template 121 has a handle 123 held by the surgeon during use,and by which the surgeon positions the template, and portion 127 thatreplicates the size and shape of ball joint portion 113 of fixationsystem 111. Portion 125 replicates the size and position of attachmentportion 107 and can be used to define where screw holes must be drilled.

At the outset, the surgeon can take a pen and draw around atemplate—normally a different template—to define the boundaries of thebone bed prior to drilling. (For example, a reliable determination ofthe perimeter would be difficult with template 121 because it will notcontact the skull surface evenly before any recessed area is drilled.Preferably a flat template that just corresponds to the topsurface/shape of the implant is used to define the perimeter of the areato be drilled.

Portion 127 of template 121 has a distal surface, 128 that contacts thesurface of the bone bed. When properly in situ, only the proximalsurface 131 of portion 127 will be visible. Thus, as the surgeon isdrilling the recessed regions, the template can be inserted to ascertainwhether portion 127 fits snugly into the respective drilled regions.Unevenness can be judged by the surgeon moving the template within thedrilled holes, and/or by testing the alignment of the upper (proximal)surface 131 of the template with the adjoining surface of therecipient's skull. The template will typically be inserted in thismanner many times during the drilling process until the surgeon issatisfied that the drilled region properly fits the implant fixationsystem, and the implant can then be attached. The template can bediscarded (in the case of a single-use embodiment), or preferablysterilized and re-used on another occasion when the same type of implantis to be installed. The implant itself is already sterilized and may notbe re-sterilized by the clinic.

In other embodiments of templates, the tool has a rocking mechanism sothat the surgeon can tell how much of the bone to drill away within therecessed area. Such a tool, however, does not reveal how even thesection is once it's drilled.

While this method of using a template is known in the art, it isimperfect because it is difficult for the surgeon to gauge accuratelywhich portions of the drilled region may be leading to an unevenness offit. Thus the surgeon may waste time drilling away portions that are notcontributing to unevenness of fit. Additionally, even where the surgeonhas drilled away portions that appear to lead to a good fit of theimplant, the surgeon has no way of identifying any cavities or crevassesin the drilled region that will create voids between the bone surfaceand the surface of the implant when affixed. Such voids are undesirabledue to the possible build up of biofilm within them, which can lead toinfections as well as imperfections of fit.

Use of a Template having a Dye on a Distal Surface

According to the instant technology, an implant template is providedthat has a dye releasing surface on one or more of the distal surfaces.See FIG. 2. When the implant template 201 is pressed into the bone bed207, the dye is transferred from the dye-releasing distal surface 209 tothe areas of protrusion 211 of the bone bed that contact the distalsurface of the template. These are protruding regions of the bone thatneed to be further flattened by drilling and are now readilyidentifiable to the surgeon as colored regions of contrast relative totheir immediate surroundings.

The manner of use of implant template 201 is as follows. The surgeonholds handle 223 of implant template 201 while applying it to the bonesurface, or bone bed. There is sufficient dye in the material on thedistal surface that the surgeon can put the template in place as manytimes as necessary during surgery.

The implant template 201 can also be used at the outset to delineate thearea of the bone to be drilled out. Prior to starting drilling, thesurgeon can place the dye-transfer material on the distal surface of theimplant on to the bone surface. The dye colors the bone surface in theshape of the implant and therefore obviates the need to delineate thatregion in some other way, such as by drawing around the template.

The instant technology can therefore lead to a reduction in time for thesurgeon to prepare the bone bed during surgery because, with eachapplication of the template, just those areas that need to be drilledare swiftly identified. This reduces aspects of trial and error from thesurgeon's task, and therefore makes for a more attractive implantchoice. The resulting better fit of an implant in the bone bed leads toless possibility of biofilm formation and less likelihood of a slippageof the implant after affixation.

Other facets of the technology are described as follows.

The dye transfer material on the distal surface of the implant templatecan take a number of different forms.

In one embodiment, the dye is absorbed into, or is coated on, somevehicle or carrier, such as an absorbent substance, referred to hereinas the dye transfer or dye-impregnated material. The dye transfermaterial is preferably a non-toxic absorbent material that is capable ofreleasing the absorbed dye with contact pressure such as when thematerial is placed in contact with another surface.

The dye transfer material is affixed, as a layer, to the distal surfaceof the template. In some embodiments the material is initially loadedwith a dye substance and, as the template is used and the dye istransferred to the bone bed, the material becomes less concentrated indye. The material can then be re-loaded with dye, as needed, such as bydipping the material in a dye-containing solution. The dye impregnatedmaterial can take the form of a sponge. In another embodiment, thedye-impregnated material is a micro fleece paper with high color storagecapacity.

Alternatively, the layer of material can be removed from the template,much as a self-adhesive sticker can be removed, and a new layer of dyetransfer material (impregnated with dye) affixed, for subsequent uses ofthe template.

In another embodiment, the surgeon is provided with a pad, impregnatedwith the dye, and on which they can contact the distal surface of thetemplate in order to coat it with dye. This can enable use of just thetemplate and the dye, without a dye-impregnated material on thetemplate. For example, when using a titanium reusable template, the dyemay simply transfer directly to the titanium surface and thereafter tothe recipient's bone bed when pressing the template onto the patient'sskull.

In still another embodiment, the dye material can be clipped onto thetemplate for example, via a press button, see FIG. 4. In this instance,the dye-impregnated material 405 is coated on a plastic carrier 401,which can be moulded with a press button 403 that clips into a matchingrecessed portion of the distal surface of the template. Such anarrangement can be suitable for a single use.

In preferred embodiments, the templates described herein are made fromstainless steel. This makes them easy to sterilize and suitable formultiple re-uses. It can be envisaged that single use templates can bemade from other materials, such as plastic.

Exemplary Dyes

Any dye used with the implant template described herein should bebiocompatible, which is to say that it should not embody any toxiceffects, should not exacerbate or create any adverse reaction in therecipient during use, and should preferably either be capable of beingrinsed or rubbed off after surgery or should remain localized at thesite of surgery, without leaching out, or should be capable of beingharmlessly absorbed within the body and naturally metabolized orexcreted out.

Articulation paper, which uses a dye-impregnated material, has been usedin dentistry for checking the ‘bite’ of a patient and has beenestablished as biocompatible. The layer of dye-impregnated materialconsists of a micronized color pigment in an oil-wax emulsion coveredwith transculase bonding agent. Such a dye transfer system can also beused in the implant template herein. Advantages of such a material arethat it has a high color storage capacity, but releases the color easilyunder pressure.

An exemplary dye paper is manufactured by Bausch GmbH, Cologne, Germany.An exemplary composition of such paper is as in Table 1:

TABLE 1 Concentration Substance CAS Number (%) Pigment Blue C.I. 2725869-00-5 10 CI Pigment red 170  2786-76-7 10 White mineral oilPharmaceutical quality 50 Natural waxes Cosmetic/pharmaceutical quality30

In other embodiments, the dye may be similar to the dyes in the pensknown in the art to outline the implant template in other types ofsurgery.

Sterile surgical skin markers for medical purposes are offered byseveral manufacturers, such as: Viscot (e.g.,www.viscot.com/1422SRL9-100), and Tondaus.

Sterile ink has been used for tattooing, and may find application in thetechnology herein, to the extent that it does not matter if the inkremains in situ at the site of surgery. There are several manufacturersof such substances: for example, Body Supply:www.bodysupply.com/colori-per-tatuaggio.html; andwww.killerinktattoo.nl/tattoo-inkt/. Some inks for tattooing aresupplied in cups that can be sterilized by ethylene oxide and aredescribed at:electrumsupply.com/sterile-single-packs-of-16-precision-ink-cup-3-×-3-sheets/

The implant template is a sterile template because it will be used in asterile area. An embodiment of the invention is a single use sterile dyetemplate that clips to an existing titanium reusable template.

Given that a template is sterilized prior to re-use, any sterilizationprocess that can wash off the dye militates in favor of either dyes thatcan survive that process, or embodiments of the implant in which a freshcoating of dye or dye-impregnated material can be introduced aftersterilization.

Exemplary Implementations

This technology is straightforward to implement and can be appliedacross a range of implant products with little difficulty. It hasapplication to any product that requires a portion of bone to be drilledaway in connection with installation. The technology therefore offersdistinct advantages over products that are not so equipped.

The technology can be applied to devices such as deep brain stimulatorsand auditory brain stem implants.

The technology can be applied to a surgically implanted microphoneand/or an implant package for an active transcutaneous bone conductiondevice, as illustrated in FIGS. 3A and 3B, respectively.

In FIG. 3A, a biocompatible implant housing 300 is locatedsubcutaneously on a patient's skull. The implant housing 300 includes asignal receiver 318 (e.g., comprising a coil element) and may include anintegrated microphone or an separate implantable microphone 310 that isinterconnected to the housing 300 via an electrical connector. In eithercase, microphone 310 will include a diaphragm 330 that is positioned toreceive acoustic signals through overlying tissue. Typically, the signalprocessor within the implant housing 100 is electrically interconnectedvia wire 106 to a transducer (not shown). A positioning system 110 isconnected to a bone anchor 116 mounted within the patient's mastoidprocess (e.g., via a hole drilled through the skull). During normaloperation, acoustic signals are received subcutaneously at themicrophone 310, which generates signals for receipt by the housing 300.Upon receipt of the signals, a signal processor within the implanthousing 300 processes the signals to provide a processed audio drivesignal via wire 306 to the transducer. Positioning of the microphone, ina bone recess, can be accomplished with the technology described herein.

In FIG. 3B, part of a transcutaneous bone conduction device is shown.External component 352 comprises an external coil 358 and operates inconjunction with an implantable component 354. The implantable component354 comprises an implantable coil 356 that is embedded within anactuator assembly 360, and can be positioned using the technologydescribed herein.

In particular, the technology can readily be used in otology inconnection with affixing implantable audio prosthetic devices, such ascochlear implants as well as middle ear implants, bone conductionimplants, direct acoustic cochlear stimulators, and vestibularstimulators.

The technology herein can also be applied to surgical templates used foractive transcutaneous bone conduction device. Exemplary such devices areprovided by Cochlear Limited. Other such devices include the fixationsystem in the Codacs™ series of products, or tools for drilling the bonebed for an active transcutaneous bone conduction device.

An active transcutaneous bone conduction device works by vibration sothe bone should not touch the surface of the implant. A screw isimplanted in the bone. All vibrational energy coming from the implantshould go via that screw into the head and not by any other contactpoints. The template for this type of implant is the same dimension asthe implant, and has a flat surface. There is less to be gained fromreduction of biofilm risk in this type implant. By contrast, the biggerrisk is that unintended contact from a piece of bone can reduce thefunctionality and impair performance of the implant.

The approach herein can also be applied to implants that are affixedwithout a pedestal, such as the Nucleus Profile implant from CochlearLimited.

The approach herein can also be applied to implants such as the CI24REfrom Cochlear Limited, which is held in place by placing skin above it,without need for screws or glue. Instead, a round bone bed is drilled sothat the implant will not move. As the implant receiver/stimulator isthe same as for the Codacs™ implant, the dye template can be used in thesame way: to first outline the shape to be drilled away, and then tocheck the depth and flatness of the bony well.

The implant template herein can be distributed in conjunction with amodel of implant. It can be accompanied, in its packaging, by anInstructions For Use booklet (IFU) for the surgeon to review. The IFUcontains instructions for how to use the implant template in conjunctionwith affixing the implant.

The implant template may also be distributed as part of a surgical kit,such as with the implant itself. In some embodiments, implant templatesare sold in a set (such as all the templates that are required for acertain type of implant), as exemplified in FIG. 5. The differenttemplates can also be ordered separately. The template can be used overand over again (i.e., on successive recipients) with the same type ofimplant or can be single use.

Preferably the implant template is sold separately, optionallyaccompanied by a selection of replacement dye material, because theimplant template may be re-used with the same type of implant to whichit is modeled. The IFU may contain instructions for re-sterilization ofthe implant template after use.

EXAMPLES Example 1: Exemplary Template set for a Codacs™ Implant System

An exemplary set of templates, of which some can be provided with adye-transfer material on their respective distal surfaces, is shown inFIG. 5. Any of the templates can be provided in kit form.

Tools and templates are available for the implant body, the fixationsystem and the actuator. The tools and templates have been designed suchthat they can be used by a right handed or left handed surgeon. Allsurgical tools and templates are from stainless steel, are reusable,re-sterilisable and are delivered unsterile. The surgical tools willtypically pre-cleaned prior to packaging to ensure that they haveundergone a degreasing process. They must also be sterilised by theclinic before use.

The BTE template 502 (see FIG. 5) is used to ensure that the implant andthe fixation system are positioned with sufficient space for an earlevel sound processor.

The implant template 504 (see FIG. 5) is used to check the shape of thewell excavation and the position of the receiver/stimulator assembly 141of FIG. 1D.

The bone recess template 506 (see FIG. 5) is used to mark the well onthe skull and to measure the depth of the well after drilling.

The array exit marking template 508 (see FIG. 5) is used to check thesize of the well excavation, select the final position of the implant byrotating the tool in the well, and mark the exit position and channelwidth for the cable that connects to the Codacs™ actuator.

A fixation system template 510 (see FIG. 5) has the same dimensions asthe real fixation system. It only represents the ball joint part,without the ball joint itself and without the clamping mechanism.

All references cited herein are incorporated by reference in theirentireties.

The foregoing description is intended to illustrate various aspects ofthe instant technology. It is not intended that the examples presentedherein limit the scope of the appended claims. The invention now beingfully described, it will be apparent to one of ordinary skill in the artthat many changes and modifications can be made thereto withoutdeparting from the scope of the appended claims.

What is claimed:
 1. A method of improving goodness of fit of an implantto a recipient's bone, the method comprising: placing a dye-impregnatedsurface of an implant template in contact with the bone so that the dyecolors the bone at points that are raised above their surroundings;drilling the colored areas in order to ensure that the surface to whichthe bone implant is affixed is smooth and has the correct width anddepth so that the implant fits well in the drilled out area and will notmove after implantation.
 2. A method for minimizing biofilm formationbetween an implant and a bone, the method comprising: placing adye-impregnated surface of an implant template in contact with the boneso that the dye colors the bone at points that are raised above theirsurroundings; drilling the colored areas in order to ensure that thesurface of the bone to which the implant is affixed is smooth andthereby does not result in pockets between the surface of the bone and asurface of the implant that is to be attached to the bone.
 3. A methodfor placing an implant, the method comprising: placing a distal surfaceof an implant template in contact with the bone, wherein the templatehas the same size and shape as the implant; delineating an area of thebone at which to affix the implant; drilling out the bone within thedelineated area in order to accommodate the implant; inserting thetemplate into the drilled out area so that a layer of dye impregnatedmaterial on the distal surface of the template is in contact with theproximal surface of the bone and the edges of the drilled out area;drilling further regions of the drilled out area that are colored by thedye; repeating the inserting and drilling further regions until thedrilled out area is uniformly coated with dye upon contact with thetemplate; and affixing the implant to the drilled out area.
 4. Themethod of claim 3, wherein the delineating includes using the dyeimpregnated template as a stamp to mark the area to be drilled out onthe bone, without needing to draw a line around the template.
 5. Themethod of claim 3, wherein the placing the distal surface of thetemplate in contact with the bone comprises contacting the layer ofdye-impregnated material on the distal surface of the template with thebone, and the delineating an area comprises identifying the area of bonethat has been colored by the dye.
 6. The method of claim 3, wherein thebone is selected from: skull, hip, jaw, and femur.
 7. The method ofclaim 3, wherein the dye is a sterile biocompatible material selectedfrom: surgical skin markers, tattoo ink, and micronized color pigment inoil-wax emulsion.
 8. The method of claim 3, wherein the dye-impregnatedmaterial is a micro fleece paper with high color storage capacity. 9.The method of claim 3, wherein the implant is an implantable hearingprosthesis.
 10. The method of claim 10, wherein the implantable hearingprosthesis is selected from: a cochlea implant, a middle ear implant, abone conduction implant and a direct acoustic cochlear implant.
 11. Themethod of claim 3, wherein the material is a sponge, a polymer, or acellulose pad.
 12. The method of claim 3, wherein the dye isbiocompatible.
 13. The method of claim 3, wherein the template is madeof titanium.
 14. The method of claim 3, wherein the repeating takesplace from 1-5 times.
 15. The method of claim 3 wherein the template hasproximal and distal surfaces, and wherein the distal surface is coveredin a dye-impregnated material, and wherein the proximal surface has anattachment member affixed to it.
 16. The method of claim 16, wherein theattachment member is held by a surgeon when placing the template incontact with the bone.
 17. A surgical tool, comprising: a first memberhaving proximal and distal surfaces, and wherein the distal surface iscovered in a dye-impregnated material, and wherein the proximal surfacehas an attachment member affixed to it, wherein the first member has thesame size and shape as an implant.
 18. The surgical tool of claim 17,wherein the first member is planar.
 19. The surgical tool of claim 17,wherein the template is made of titanium.
 20. The surgical tool of claim17, wherein the dye-impregnated material is a sponge, a polymer, or acellulose pad.
 21. The surgical tool of claim 17, wherein thedye-impregnated material is a micro fleece paper with high color storagecapacity.
 22. The surgical tool of claim 17, wherein the dye isbiocompatible.
 23. The surgical tool of claim 17, wherein the dye is asterile biocompatible material selected from: surgical skin markers,tattoo ink, and micronized color pigment in oil-wax emulsion.
 24. Asurgical kit, comprising: a dye; and a surgical template comprising afirst member having distal and proximal surfaces, and wherein the distalsurface is covered in an absorbent material, and wherein the proximalsurface has an attachment member affixed to it, wherein the first memberhas the same size and shape as a bone implant.
 25. The surgical kit ofclaim 24, wherein the first member is planar.
 26. The surgical kit ofclaim 24, further comprising the bone implant.
 27. The surgical kit ofclaim 24, wherein the absorbent material is a sponge, a polymer, or acellulose pad.
 28. The surgical kit of claim 24, wherein the absorbentmaterial is a micro fleece paper with high color storage capacity. 29.The surgical kit of claim 24, wherein the dye is biocompatible.
 30. Thesurgical kit of claim 24, wherein the dye is a sterile biocompatiblematerial selected from: surgical skin markers, tattoo ink, andmicronized color pigment in oil-wax emulsion.